> http://telemedicine.orbis.org/bins/volume_page.asp?cid=1-178-874-1014
>
> 36-year-old female presents for her annual eye exam. She reports that
> she has been wearing her extended-wear contacts "for months at a time"
> but denies any change in vision or eye pain. Upon examination, the
> corneal findings are as shown above.
Yet another "Aceism."
The patient in question was shown wearing an RGP lens. The vessels
were extending from the temporal limbus to the edge of the contact
lens, and not underneath the lens. Therefore, the mechanism was most
likely not hypoxia, or lack of oxygen, but dryness resulting from
improper lubrication of the corneal surface in that area. This is a
typical location for exposure keratitis in a patient wearing a small
corneal lens. If the problem had been caused by hypoxia -- or lack of
oxygen, the vessels would have extended beneath the surface of the
lens, and those vessels would have been widely distributed in a
configuration known as pannus.
There are three brands of contact lenses approved for 30 days of
continuous wear by the FDA. Those are Menicon Z, Purevision, and Focus
N&D. All of them have sufficient oxygen permeability NOT to cause
hypoxia-related neovascularization. However, staining in the 3:00 -
9:00 regions are characteristic of smaller corneal lenses, not soft
lenses.
Unfortunately, Ace gets it wrong so often, that nearly half the
responses in any group in which he participates are corrections to his
posts. He is the embodiment of the phrase, a little knowledge is a
dangerous thing. I sure hope he doesn't play with matches.
DrG